Without knowing your budget it's hard to make recommendations. I would suggest going here: http://pcpartpicker.com/

It's a great site and there are even some builds listed on the front page for various price points. Once you create the build you want, the site updates prices of your components from a number of different retailers and even shows discounts and combo pricing. Also, you can view other peoples builds for ideas and get feedback/suggestions on your build.

You may also want to check out Tom's Hardware. They do a lot of different priced builds and have pretty decent reviews on components.

Good luck!